textproduct: Rapid City

KEY MESSAGES

- Cool tomorrow (Thursday) with highs in the 70s to low 80s across much of the area

- Showers/storms move through tonight into tomorrow. Severe weather isn't expected, though some storms may be capable of localized heavy downpours.

- Hot and dry conditions through the weekend and into the first of next week still look likely.

UPDATE

Issued at 1040 PM MDT Wed Jul 22 2026

Regional weather radar depicts showers and a few storms moving into northeastern WY as an upper level wave and monsoonal moisture moves into the Northern Plains. Showers/storms should push into western SD overnight as the wave moves through. Severe threat is minimal overnight into tomorrow as deep layer shear is lacking. Evening soundings for our office and surrounding offices depict PWATs ranging from 1.2 to 1.6" which is around 150-175% of normal for this time of year. This should support locally heavy downpours. However, due to the convective nature of the rainfall, while some spots might "boom" and get up to an inch or more of localized precip, other spots might not see much, if any, rain. Current guidance shows most likely areas to see widespread wetting precip will be across the Black Hills and along and south of the I-90 corridor in western SD where QPF of 0.25+" is possible in some spots.

Still looking like this weekend will be hot with temperatures reaching the triple digits across much of the western SD plains into northeastern WY by Saturday and Sunday. Heat headlines may be needed for the weekend. In addition to the very hot temperatures, very dry air is also expected with minimum humidities progged to range from 15 to 20% across much of the area. While winds this weekend might not quite make it to our critical criteria, we could still see widespread elevated to near critical fire weather conditions develop across much of the area this weekend into early next week.

DISCUSSION

(This Evening Through Wednesday) Issued at 116 PM MDT Wed Jul 22 2026

Latest water vapor imagery shows center of upper high pressure located across nrn TX/OK with ridge axis pointed northeast into Pacific NW. Monsoonal moisture continues to stream around the periphery of the ridge. Minor waves are located across eastern ID/southwest MT/western WY with another lifting northward through UT. At the surface, high pressure located across the eastern Dakotas with a weak lee trough located along the Big Horns. Temperatures at 18Z across the CWA range from the 60s in the cloud covered areas across the east, to the mid 70s to lower 80s in the partly cloudy areas.

The biggest issue facing the near-term forecast will be the expected rainfall overnight into Thursday. Models have backed off on strength/timing and track of the wave now moving through MT/WY. Deterministic models now have this feature sliding just a bit further south than previous runs, taking expected rainfall also a bit further south. Expected pwats are still high, running 150-200% of normal overnight through Thursday. Ensembles show probability of 1.75"+ pwats increasing to 60-90% during the day Thursday across our southern counties. However, ensembles also show probabilities of receiving 0.25" or higher pcpn only on the order of 30-40%, and again mainly relegated to areas mainly south of I-90. Things remain pretty transitory so not too worried about any flooding/flash flooding issues. Still wouldn't be surprised to hear of some localized 1"+ rainfall amounts by the close of day Thursday, but thinking now it won't be as widespread as earlier thought.

After that, hot and dry will be the rule heading into next week. With a more spotty nature to the rainfall, there may not be as much moisture to burn off on Friday than previously thought. Deterministic models have actually trended higher for forecasted highs on Friday. With 700hpa temps pushing +20C and 850hpa temps +36C by 00Z Sunday, not concerned about any convection developing over the Black Hills. Will most likely need heat headlines (again) for the upcoming weekend.

AVIATION

(For the 06Z TAFS Through 06Z Thursday Night) Issued At 955 PM MDT Wed Jul 22 2026

Light showers have moved into northeastern WY and will spread into western SD. SHRA is expected to continue through the night and potentially through Thursday afternoon, particularly in SD. Conditions will largely be VFR, but MFVR/IFR conditions may be possible near stronger precipitation.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.